// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// A set of classes for quantizing and dequantizing of floating point values
// into integers.
// The quantization works on all floating point numbers within (-range, +range)
// interval producing integers in range
// (-max_quantized_value, +max_quantized_value).

#ifndef DRACO_CORE_QUANTIZATION_UTILS_H_
#define DRACO_CORE_QUANTIZATION_UTILS_H_

#include <stdint.h>
#include <cmath>

#include "draco/core/macros.h"

namespace draco {

// Class for quantizing single precision floating point values. The values must
// be centered around zero and be within interval (-range, +range), where the
// range is specified in the Init() method.
class Quantizer {
  public:
    Quantizer();
    void Init(float range, int32_t max_quantized_value);
    inline int32_t QuantizeFloat(float val) const {
        const bool neg = (val < 0.f);
        if (neg) {
            val = -val;
        }
        val /= range_;
        const int32_t ret = static_cast<int32_t>(
                                floor(val * static_cast<float>(max_quantized_value_) + 0.5f));
        if (neg)
            return -ret;
        return ret;
    }
    inline int32_t operator()(float val) const {
        return QuantizeFloat(val);
    }

  private:
    float range_;
    int32_t max_quantized_value_;
};

// Class for dequantizing values that were previously quantized using the
// Quantizer class.
class Dequantizer {
  public:
    Dequantizer();

    // Initializes the dequantizer. Both parameters must correspond to the values
    // provided to the initializer of the Quantizer class.
    // Returns false when the initialization fails.
    bool Init(float range, int32_t max_quantized_value);
    inline float DequantizeFloat(int32_t val) const {
        const bool neg = (val < 0);
        if (neg) {
            val = -val;
        }
        float norm_value = static_cast<float>(val) * max_quantized_value_factor_;
        if (neg)
            norm_value = -norm_value;
        return norm_value * range_;
    }
    inline float operator()(int32_t val) const {
        return DequantizeFloat(val);
    }

  private:
    float range_;
    // Distance between two normalized dequantized values.
    float max_quantized_value_factor_;
};

}  // namespace draco

#endif  // DRACO_CORE_QUANTIZATION_UTILS_H_
